1. Field of the Invention
The present invention relates to a device for applying active substances to surfaces of medical implants, in particular stents, with a holder for the implants, an arrangement for applying the active substance onto the surface, and a drive unit for moving the holder and the arrangement relative to one another.
2. Related Prior Art
Such a device is known from U.S. Pat. No. 6,395,326 and from DE 202 00 223 U1.
The known devices are provided for coating stents, that is to say vascular prostheses, with medicaments. Such coatings are desirable because, in the first instance, they can improve the biocompatibility of the implants, for example so as to prevent development of thromboses in the case of surfaces coming into contact with blood.
Particularly in the case of stents, it is also known to coat their surfaces with medicaments, for example rapamycin, in order to prevent restenosis through proliferation of the surrounding tissue. Moreover, suitably coated stents are able to deliver medicaments in a targeted manner in situ into the surrounding tissue.
Stents which can be provided with a coating of different active substances have been described by many authors in the prior art; see, for example, DE 202 00 220 U1, EP 0 875 218 A2 or EP 0 950 386 A2.
Other medical implants also often require a suitable surface coating because they have to be biocompatible and their surfaces do not provide for this in the original state. Thus, in the context of the present application, an implant is to be understood as meaning not just prostheses which remain permanently in the patient's body, but also other devices which remain in the body for some time, for example pace makers, heart catheters, any kind of catheter, screws for orthopedic application, long-term catheters, which are used for intra-venous feeding, etc., of seriously ill, paralyzed or unconscious patients, and the like more.
In the aforementioned, known devices, the active substance is sprayed via a nozzle onto the outer surface of the stent, where it settles and dries on. To do this, a relative movement between nozzle and stent is needed in the longitudinal direction of the stent, and the stent has to be rotated in the jet of the nozzle, or the nozzle has to be rotated.
It has been found now that the known devices in many respects do not satisfy the latest requirements when using implants in general, in particular stents, and they especially do not satisfy the increasingly necessary or desired flexibility and individual adaptability in the coating. In addition, the known devices are not safe enough in terms of their use by the physician because the latter may come into contact with the active substances, which entails great risks, for example in the case of coatings with adenoviruses. Finally, the known devices are unsatisfactory purely from the point of view of mechanics, hygiene and sterility.